Because the Moon is tidally locked,
it was not until 1959 that the farside was first
by the Soviet Luna 3 spacecraft (hence the Russian names for prominent
farside features, such as Mare
Moscoviense). And what a
surprise - unlike the widespread maria
on the nearside, basaltic volcanism was restricted to a relatively few,
smaller regions on the farside, and the battered highlands crust
dominated. A different world from what we saw from Earth.
Of course the cause of the
farside/nearside asymmetry is an interesting scientific question. Past
studies have shown that the crust on the farside is thicker, likely
making it more difficult for magmas to erupt on the surface, limiting
the amount of farside mare basalts. Why is the farside crust thicker?
That is still up for debate, and in fact several presentations at this
week's Lunar and Planetary Science Conference
attempt to answer this question.
mission obtained beautiful mosaics with the sun high in the sky (low
phase angles), but did not have the opportunity to observe the farside
at sun angles favorable for seeing surface topography. This WAC mosaic
provides the most complete look at the morphology of the farside to
date, and will provide a valuable resource for the scientific
community. And it's simply a spectacular sight!
Arizona State Univ. /